Instead of regular centralize stablecoins, why we don't have a stablecoin with its own blockchain or a token where anyone can mint or redeem that stablecoin using ONLY Cryptocurrencies at the market price.
For example if I have 1 Eth and want to mint it into Xusd (community stablecoin) it goes like this example:
If Eth market price = $1000 I send 1 Eth to this blockchain or contract and I receive 1000 Xusd.
And it can be redeem for any Crypto at market price,
If Eth price = $2000 I send 1000 Xusd and get 0.5 Eth.
It can be done with a asset that is stable in price. With a volatile asset like ETH or Bitcoin this can be challenging because those stablecoins needs to be backed by collateral assets. So if it is backed by ETH and the price of ETH goes down and its TVL goes down than the total amount of Xusd minted then the protocol will be under collateralized. That means all the Xusd holders will not be able to cash out or redeem their Xusd. It is not that simple, as the OP is thinking.